Stroke occurs in 1-6% of patients undergoing surgery. As many as three out of four patients demonstrate neurologic injury in the week following cardiopulmonary bypass (CPB) with one out of five patients exhibiting permanent neurobehavioral dysfunction. The most obvious etiologic factor appears to be emboli originating from the surgical field and the CPB circuit. We propose to protect the brain and heart during cardiac procedures by eliminating or redirecting emboli as well as minimizing the trauma caused by emboli that do reach the brain. Cerebral hypothermia is the most potent, established tool in achieving neuroprotection because it decreases blood flow and metabolism, thereby reducing embolization. Further, hypothermia reduces the size of ischemic lesions. However, systemic normothermia appears to offer several advantages to the patient; a shorter operative time with improved myocardial and respiratory outcome accompanied by a reduction in postoperative bleeding. Unfortunately, normothermic CPB may place the patient at risk for neurologic deficit. A CPB technique that allows for cerebral hypothermia and systemic normothermia may optimize clinical outcome. This study will develop methods and apparatus for differential perfusion of the aortic arch and corporeal circulations using a triple lumen catheter which will reduce cerebral embolization. PROPOSED COMMERCIAL APPLICATIONS: Over half of the 500,000 patients undergoing CPB last year in the USA had evidence of brain injury (l). The successful development of a method to reduce brain injury will have a major impact on patient outcome and health care resources. Unlike therapeutic interventions, a method of differential cerebral and corporeal perfusion using a multiple lumen catheter would be rapidly applicable to clinical CPB requiring only minimal training and adjunctive apparatus and be relatively inexpensive.